Optical discs conforming to various standards, such as compact disc (CD), digital versatile disc (DVD), and Blu-ray disc standards, have been developed. The discs compliant with these standards are functionally divided into playback-only discs and recordable discs. The recordable discs are further divided into write-once discs in which data can be recorded only once and rewritable discs in which data can be rewritten.
For example, in the CD standard, compact discs digital audio (CD-DAs) and compact discs-read only memory (CD-ROMs) are classified into the playback-only discs, compact discs recordable (CD-Rs) are classified into the write-once discs, and compact discs rewritable (CD-RWs) are classified into the rewritable discs.
Generally, data on the playback-only discs cannot be physically rewritten because the data is represented by using embossed pits.
In the write-once discs, color-change recording layers are irradiated with laser light to cause changes in color in the recording layers in order to form pits.
In the rewritable discs, phase-change recording layers are irradiated with laser light to cause changes in phase in the recording layers in order to form pits (rewrite data).
Since the data on the rewritable discs can be rewritten any number of times, the data can be flexibly stored on the discs to provide superior usability.
In contrast, data can be recorded only once on the write-once discs. However, the advantage of disabling rewriting of the data is used to provide media suitable for data storage. For example, the write-once discs are suited to store important data which is desirable not to be falsified.
With regard to the recording operation of the rewritable discs, a technique in which the property in that repeatedly recording data on the same section deteriorates the phase-change recording layer is considered to vary the start point of recording is disclosed in Japanese Unexamined Patent Application Publication No. 8-10489.
The physical structure (the color change layer) of the write-once disc differs from that (the phase change layer) of the rewritable disc and the difference is defined in the respective discs. However, there is a request to perform the write-once recording on the rewritable disc.
Writing data on the rewritable disc only once can be achieved by, for example, a recording apparatus (disc drive apparatus) that controls the recording operation by using software. In other words, in order to use the loaded rewritable disc as a write-once disc, firmware that disables writing of data in areas where data has already been recorded, that is, firmware that disables rewriting of data is installed in the disc drive apparatus.
However, only the installation of the firmware cannot adequately use the advantage of the write-once disc.
It is important to take the advantage of blocking of falsification of data in the use of the rewritable disc as the write-once disc.
When the rewritable disc on which data can be physically rewritten is used as the write-once disc by controlling the installed firmware in a certain disc drive apparatus, rewriting of data (falsification of data) is not disabled. In other words, if the rewritable disc that is controlled by using the firmware such that data cannot be rewritten on the rewritable disc in a certain disc drive apparatus is loaded in a disc drive apparatus that does not assume the use of the rewritable disc as the write-once type, the rewritable disc is processed as the normal rewritable disc. As a result, rewriting of the data is attained on the rewritable disc.
Accordingly, there is little point in intentionally using the rewritable disc as the write-once disc.
There is a request to use the disc on which data can be physically rewritten as the write-once disc, and such request can be easily accommodated only in a certain disc drive apparatus. However, since the rewriting of data on such a disc cannot be disabled in all existing disc drive apparatuses, it is presumed that it is difficult to accommodate the above request.
Since the rewriting of data on such a disc cannot be disabled, it is presumed that it is difficult to accommodate the above request.